Journal of Zhejiang University. Science最新文献

Objective: To investigate the anti-tumor efficacy of dendritic cell (DC)-based vaccines pulsed with tumor extracts or RNA in a mouse model of intracranial G422 glioblastoma.

Methods: Bone marrow-derived DCs were pulsed ex vivo with tumor extracts or RNA. Ninety female mice harboring 4-day-old intracranial G422 glioblastomas and 126 normal mice were treated with three spaced one week apart subcutaneous injections either with PBS, unpulsed DCs, G422 tumor extracts, RNA, DCs pulsed with G422 tumor extracts (DC/extract) or with RNA (DC/RNA). Seven days after the third immunization of normal mice, the spleens of 36 of them were harvested for cytotoxic T lyphocyte (CTL) assays and the others were challenged in the brain with G422 tumor cells. All the treated mice were followed for survival. Some mice brains were removed and examined pathologically when they died.

Results: Immunization using DC/extract or DC/RNA significantly induced G422-specific CTL responses compared with control groups (P<0.01). Vaccination with DC/extract or DC/RNA, either prior to G422 tumor challenge or in tumor-harboring mice, significantly prolonged survival compared with other control groups (P<0.01).

Conclusion: DCs pulsed with tumor extracts or RNA derived from autologous tumors has potential antitumor effects via activation of cell-mediated immunity. Our results suggest a useful therapeutic strategy against gliomas.

The morphology and ultrastructure of Bullacta exarata spermatozoa observed by light and transmission electron microscopy are presented in this paper. The spermatozoa is composed of head with a simple acrosomal complex and an elongated nucleus, and tail with a midpiece, principal piece and an end piece. The midpiece consists of a mitochondrial ring, and the principal piece is composed of axoneme and lateral fin. The structure of B. exarata spermatozoa differs significantly from that of other gastropods, especially in the lateral fin and the principal piece, which was described scarcely before. A comparison is made between B. exarata and other gastropods, and its significance on reproductive evolution and physio-ecological adaptation is preliminarily discussed.

Fibrillar proteins form structural elements of cells and the extracellular matrix. Pathological lesions of fibrillar microanatomical structures, or secondary fibrillar changes in globular proteins are well known. A special group concerns histologically amorphous deposits, amyloid. The major characteristics of amyloid are: apple green birefringence after Congo red staining of histological sections, and non-branching 7-10 nm thick fibrils on electron microscopy revealing a high content of cross beta pleated sheets. About 25 different types of amyloid have been characterised. In animals, AA-amyloid is the most frequent type. Other types of amyloid in animals represent: AIAPP (in cats), AApoAI, AApoAII, localised AL-amyloid, amyloid in odontogenic or mammary tumors and amyloid in the brain. In old dogs Abeta and in sheep APrPsc-amyloid can be encountered. AA-amyloidosis is a systemic disorder with a precursor in blood, acute phase serum amyloid A (SAA). In chronic inflammatory processes AA-amyloid can be deposited. A rapid crystallization of SAA to amyloid fibrils on small beta-sheeted fragments, the 'amyloid enhancing factor' (AEF), is known and the AEF has been shown to penetrate the enteric barrier. Amyloid fibrils can aggregate from various precursor proteins in vitro in particular at acidic pH and when proteolytic fragments are formed. Molecular chaperones influence this process. Tissue data point to amyloid fibrillogenesis in lysosomes and near cell surfaces. A comparison can be made of the fibrillogenesis in prion diseases and in enhanced AA-amyloidosis. In the reactive form, acute phase SAA is the supply of the precursor protein, whereas in the prion diseases, cell membrane proteins form a structural source. Abeta-amyloid in brain tissue of aged dogs showing signs of dementia forms a canine counterpart of senile dementia of the Alzheimer type (ccSDAT) in man. Misfolded proteins remain potential food hazards. Developments concerning prevention of amyloidogenesis and therapy of amyloid deposits are shortly commented.

Objective: Embryonic chromosomal abnormality is one of the main reasons for in vitro fertilization (IVF) failure. This study aimed at evaluating the value of Fluorescence in-situ Hybridization (FISH)-based Preimplantation Genetic Diagnosis (PGD) in screening for embryonic chromosomal abnormality to increase the successful rate of IVF.

Method: Ten couples, four with high risk of chromosomal abnormality and six infertile couples, underwent FISH-based PGD during IVF procedure. At day 3, one or two blastomeres were aspirated from each embryo. Biopsied blastomeres were examined using FISH analysis to screen out embryos with chromosomal abnormalities. At day 4, embryos without detectable chromosomal abnormality were transferred to the mother bodies as in regular IVF.

Results: Among 54 embryos screened using FISH-based PGD, 30 embryos were detected to have chromosomal abnormalities. The 24 healthy embryos were implanted, resulting in four clinical pregnancies, two of which led to successful normal birth of two healthy babies; one to ongoing pregnancy during the writing of this article; and one to ectopic pregnancy.

Conclusion: FISH-based PGD is an effective method for detecting embryonic chromosomal abnormality, which is one of the common causes of spontaneous miscarriages and chromosomally unbalanced offsprings.

System identification is a method for using measured data to create or improve a mathematical model of the object being tested. From the measured data however, noise is noticed at the beginning of the response. One solution to avoid this noise problem is to skip the noisy data and then use the initial conditions as active parameters, to be found by using the system identification process. This paper describes the development of the equations for setting up the initial conditions as active parameters. The simulated data and response data from actual shear buildings were used to prove the accuracy of both the algorithm and the computer program, which include the initial conditions as active parameters. The numerical and experimental model analysis showed that the value of mass, stiffness and frequency were very reasonable and that the computed acceleration and measured acceleration matched very well.

A new neural network based method for solving the problem of congestion control arising at the user network interface (UNI) of ATM networks is proposed in this paper. Unlike the previous methods where the coding rate for all traffic sources as controller output signals is tuned in a body, the proposed method adjusts the coding rate for only a part of the traffic sources while the remainder sources send the cells in the previous coding rate in case of occurrence of congestion. The controller output signals include the source coding rate and the percentage of the sources that send cells at the corresponding coding rate. The control methods not only minimize the cell loss rate but also guarantee the quality of information (such as voice sources) fed into the multiplexer buffer. Simulations with 150 ADPCM voice sources fed into the multiplexer buffer showed that the proposed methods have advantage over the previous methods in the aspect of the performance indices such as cell loss rate (CLR) and voice quality.

This paper presents the construction of a pneumatic active suspension system for a one-wheel car model using fuzzy reasoning and a disturbance observer. The one-wheel car model can be approximately described as a nonlinear two degrees of freedom system subject to excitation from a road profile. The active control is composed of fuzzy and disturbance controls, and functions by actuating a pneumatic actuator. A phase lead-lag compensator is inserted to counter the performance degradation due to the delay of the pneumatic actuator. The experimental result indicates that the proposed active suspension improves much the vibration suppression of the car model.

This study aimed at investigating the characteristics of table and graph that people perceive and the data types which people consider the two displays are most appropriate for. Participants in this survey were 195 teachers and under-graduates from four universities in Beijing. The results showed people's different attitudes towards the two forms of display.

A network model is proposed to support service differentiation for mobile Ad Hoc networks by combining a fully distributed admission control approach and the DIFS based differentiation mechanism of IEEE802.11. It can provide different kinds of QoS (Quality of Service) for various applications. Admission controllers determine a committed bandwidth based on the reserved bandwidth of flows and the source utilization of networks. Packets are marked when entering into networks by markers according to the committed rate. By the mark in the packet header, intermediate nodes handle the received packets in different manners to provide applications with the QoS corresponding to the pre-negotiated profile. Extensive simulation experiments showed that the proposed mechanism can provide QoS guarantee to assured service traffic and increase the channel utilization of networks.

This paper presents an efficient parallel algorithm for the shortest-path problem in interval graph for computing shortest-paths in a weighted interval graph that runs in O(n) time with n intervals in a graph. A linear processor CRCW algorithm for determining the shortest-paths in an interval graphs is given.